Manufacture of continuously-loaded electrical conductors



Oct. 30, 1928. o. E. BUCKLEY MANUFACTURE OF CONTINUOUSLY LOADED ELECTRICAL 'CONDUGTORS Filed Jan. 31, 1924 Wren/0r Patented Oct. 30, 1928.

UNITED STA ES PATENT OFFICE.

OLIVER E. BUCKLEY, OF MAPLEWOOD, NEW JERSEY, ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. 21, A CORPORATION OF NEW YORK.

MANUFACTURE OF CQNTIN'UOUSLY-LOADED ELECTRICAL CONDUCTORS.

Application filed January 31, 1924.

This invention relates to the demagnetization of continuously loaded electrical conductors.

In the development of the signaling art it has been found highly desirable to load electrical transmission circuits with magnetic material. lVith respect to current waves of a given range of frequencies, the length of the transmission circuits may be increased in this manner or, for a given length of circuit, the range of frequencies which can be transmitted over a given circuit can be extended. In any event, the length of the circuit is determined by the allowable distortion and attenuation of the transmitted waves. It is well known that uniformity throughout the length of the circuit is necessary in order to realize to the fullest extent the advantages to be gained from loading.

Recently a very great step forward has been made in the art ofloading by the invention of a loaded conductor in which the loading material consists of an alloy of nickel and iron. This material has a very high permeability for small magnetizing forces and is known as permalloy. For further particulars, reference may be had to an article by H. D. Arnold and G. W. Elmen entitled Permalloy, an alloy of remarkable magnetic properties, which was published in the Journal of the Franklin Institute for May, 1923.

In the art of submarine telegraphy, another great step forward has been taken by the invention of a permalloy loaded submarine telegraph cable. As a result of'this inven tion, signaling speeds have been increased many-fold. Features of this invention are fully described in applicants copending applications Serial Nos. 492,7 25 and 492,726 both filed August 16, 1921, and which have issued as Patents 1,586,874 and 1,586,875, re-' spectively, on June 1, 1926.

The necessity for uniformity in the loading throughout the length of the circuit is also present in submarine telegraph cables. Much thought and effort has been expended to accomplish this condition. As pointed out in the publication and applications, supra, permalloy loaded conductors are subject to considerable change in constants due to change in permeability on account of mechanical strains to which thematerial is subjected in the course of manufacture.

The eflect of the strains encountered in Serial No. 689,620.

manufacture is in general to decrease the permeabllity and lower the inductance of the cable. Provided that the strain to which the loading material has been subjected has not exceeded the elastic limit, this loss of permeability may be regained by demagnetization after the strain is removed.

in more rare cases certain strains actually raise the inductance and in this case it is lowered by demagnetization. The effect of handling the cable is thus in general to lower the inductance and to make it less uniform. he effect of demagnetization is in general to raise the inductance and to make it more uniform. Likewise, during heat treating and testing, the loading material may inherently or accidentally be subjected to large magnetizing forces which cause changes in its permeability. Such change may also be largely compensated for by demagnetization.

An object of this invention is to bring all sections of the loaded conductor to as uniform a condition as possible.

Another object is to subject the loaded conductor to a novel demagnetizing process, preferably after incorporation in the completed cable and as nearly as possible at the end of the period of handling.

According to one embodiment of this inven tion, the completed. cable is passed lengthwise through a solenoidal coil as the cable passes from the factory to the cable ship. The coil is energized by alternating current of sufficient strength to magnetically saturate the loading material. As each elemental length of the cable passes away from the magnetizing coil, it is subjected to a progressively, decreasmagnctic field which effects demagnetization in a simple and effective manner.

The novel features which are considered characteristic of this invention are set forth with particularity in the appended claims.

The invention, both as to its organization and operation, together with other objects and advantages thereof, will be further explained in the following description having reference to the accompanying drawing consisting of he following figures.

Fig. 1 shows schematically one embodiment of the invention as applied to the manufacture and handling of continuously loaded submarine cable.

Figs. 2, 3 and 4: show the detailed construction of one type of demagnetizing coil.

Fig. 5 illustrates a section of submarine telegraph cable adaptable to treatment according to this invention.

Referring now to Fig. 1 a continuously loaded submarine cable 5 is shown in the process of being transferred i'rom a water storage tank 6 in a factory to a cable ship 7. As the cable passes iirom the factory to the ship, it is passed through a coil 8 which is shown connected to electrical power main 9 by a switch 10.

i The detailed construction of the coil 8 is shown in Figs. 2, 8 and 4. Like reference characters are used in the several figures.

Upon a central brass sleeve if, 2 inches inside diameter by 7%.; inches long, are placed seven phenol fibre washers 12,- each of which is a tenth of an inch thick with an outside diameter of about 4 inches. These washers are separated and held in position by split phenol fibre bushings 13 and phenol fibre spacers 14. The brass sleeve 11 is split throughout its length and the space 15 is filled by the phenol fibre spacers A. The washers, bushings, and spacers are held in place by split brass nuts 16 which are screwed on to the ends of sleeves 11. Care must be taken to insure that the slit 15 in the sleeve 11 registers with the slit in the brass washers as shown in Fig. 4.

Six winding spaces 17 are thus provided, in each of which are placed 1,000 turns of No. 26 double cotton covered copper wire. These windings are connected in aiding rela tionship. The four sections at one end are connected in parallel with each other and the two sections at the other end are likewise connectcd in parallel thus forming two groups.

The two groups are connected in series, the

tree terminals of which are connected re spectively to the binding posts 18. Binding posts 18are mounted on a phenol fibre covering 19 which serves also to protect the windings from mechanical injury. The coil shoulc be impregnated with a water proofing compound to prevent water from the wet cable passing through the coil and causing short circuiting of its turn.

When the terminals 18 are connected to an ordinary 110 volt (30 cycle power main, the current flowing through this coil is about two and one quarter amperes. This amount of current is sufiicien't to saturate the loading material of cable 5.

In certain cases it may be possible to accomplish the desired result without saturating the magnetic material, in which case the design of the coil would be suitably changed.

The cable 5, details of which are shown in Fig. 5, comprises a central copper conductor 21 surrounded by a plurality of helically applied segmented conducting strips which cooperate with conductor 21 to form a flexible conductor of sutlicient conducting cross section. Surrounding the flexible conductor is the loading material 23 which is preferably in the form of a helically applied tape wound about the fiexible conductor. This tape con sists of permalloy as described in applicants copending application supra.

Surrounding the loaded conductor isathin layer of a semi-fluid compound 24 which also fills all the interstices of the conductor. Its purpose is to provide a uniform distribution of pressure about the permalloy tape when the cable is subjectedto pressure as in immersion in great depths of water. Outside the layer of compound 24L is the insulating covering 25 of guttapercha. Over thegutta perch-a insulating covering is a jute serving 26 which provides a foundation for the armor wires 27. Outside the armor wires is an other jute serving 28. Each armor wire may be provided with a wrapping of fabric to space adjacent armor wires and to enable them to approach each other without cramp mg.

Each elemental length of the cable 5 enters the coil 8 at the end having two sections connected in parallel and passes out from the end having four sections in parallel. In this way, each elemental section of the cable 5 passes from a magnetic field of maximum intensity to one of less intensity, the influence of the current in the coil 8 being felt for a considcrable distance beyond the coil, but gradually decreasing as the distance from the coil is increased until it passes entirely beyond the in fiucnce of the coil. Thus, during the passage from a point of strong field to a point of zero field the magnetic fiux in theloading material is gradually reduced in magnitude while rapidly alternating in direction, giving just the desired condition for effective demagnetization.

It should be noted that whereas the field due to a current in the conductor, as in the case of chance magnetization during tests, is at right angles to the field due to the current in the coil surrounding it, the direction of the magnetic flux is not verydifi'erent in the two cases for a conductor loaded with a helical tape or wire or high permeability. In both cases the lines of induction closely follow the tape and consequently demagnetization by a field parallel to the conductor will be eitective tor removing magnetization caused by a current tlowing through the conductor. However, even in a loaded conductor having a uniform continuous cylinder oi loading material around the conductor in which there is no air gap, the method of demagnetization according to this invention, would be effective since the etlect of magnetization in the direction at right angles to the axis of the conductor could be completely removed by saturating the magnetic material in a direction parallel to the axis of the conductor and then demagnetizing in the manner hereinbefore described.

Other embodiments of the invention will now be obvious to those skilled in the art. For example, the coil 8 might be located out board of the cable ship and become effective just before each elemental length of the cable 5 goes under water during the process of laying the cable. On the other hand, the invention might be used to demagnetize the loaded conductor at some other point in the process of manufacture and handling.

Although the process of treating a loaded conductor in accordance with the method herein described is spoken of as a demagnetizing process this terminology is used because of the analogy of the physical opera tion with demagnetization as it has been pre viously practiced in connection with bodies of magnetic material such as clocks and watches or parts thereof, this is no definite representation that the useful results of applieants invention were wholly or partly an actual physical demagnetization. However it is considered that at least some of the desirable results are due to demagnetization although some may be due to other effects. An essential feature of the invention is that the application of the herein described process to a loaded conductor after the conductor has been armored and insulated improves the magnetic characteristics of the conductor.

What is claimed is:

1. In a method of manufacturing a continuously loaded conductor, the step of improving the magnetic properties of said loaded conductor throughout its length by passing it through a magnetizing coil.

2. In a method of manufacturing a continuously loaded conductor, the step of unifying the magnetic properties of said loaded conductor throughout its length by subjecting successive elements of said loaded conductor to a gradually diminishing, alternating, magnetic field.

3. The method of improving the inductance of a continuously loaded conductor having a loading material with a permeability which is sensitive to mechanical strains, said method comprising guiding the loaded conductor through a magnetizing coil, subjecting successive portions of said conductor to an alternating magnetic field in said coil of such strength that said loading material becomes saturated, and gradually removing said portions from the influence of said field.

4. The method of unifying the electrical properties of a continuously loaded conductor having a loading material with a permeability higher than that which can be obtained in iron and easily deteriorated by mechanical strains in said material, said method comprising unifying the permeability of said material throughout a length of said conductor by passing said conductor through an alternatin magnetic field of sufficient intensity to saturate said loading ma terial, said conductor being passed in a direction substantially parallelto the direction of I said field.

5. The method of improving the electrical characteristics of a completed continuously loaded cable having a loading material comprising a magnetic composition which has a permeability at low magnetizing forces higher that iron and highly sensitive to mechanical strains in said material, said method comprising guiding the completed cable through a magnetizing coil, subjecting for a short period of time successive portions of said cable to an alternating magnetic field within said coil of an intensity sufiicient to saturate said loading material, then subjecting said portions for a longer period of time to a less intense field Within said coil and then gradually removing said portions from the influence of said coil.

6. In an arrangement for improving the magnetic condition of the loading material upon a magnetically loaded signaling conductor, means for producing a magnetic field in a definite localized portion of space, and means for guiding the conductor longitudinally through said portion.

1 In an arrangement for improving the magnetic condition of a continuously loaded conductor, means for producing a localized alternating magnetic field, and means for guiding a continuously loaded conductor lengthwise through said field.

8. In an arrangement for unifying the inductance of a conductor continuously loaded with a magnetic material, the permeability of said material being highly sensitive to mechanical strains, a magnetizing coil for producing an alternating magnetic field within said coil, means for guiding said conductor for its full length through said coil in a direction parallel to the direction of said field, whereby the permeability of said loading material may be brought to substantially the same condition throughout a length of said loaded conductor.

9. In an arrangement for improving the electrical characteristics of a completed con tinuously loaded submarine cable having a loading material comprising a nickel and iron compound with a permeability higher the that which can be obtained in iron and highly sensitive to mechanical strains, a coil surrounding a portion of said completed cable, and means to energize said coil to pro duce an alternating magnetic field within said coil to magnetically saturate the loading material, means for guiding said cable lengthwise through said coil, whereby the permeability of said loading material may be improved throughout a length of said completed cable.

In witness whereof, I hereunto subscribe my name this 29th day of January, A. D. 1924.

OLIVER .E. BUCKLEY. 

